What is the Hard Drive?

Posted By BrokenClaw on September 14, 2007

The hard disk drive (abbreviated HDD), more commonly called the hard disk or hard drive, is the device that stores the operating system, your software, and your data files. It is a magnetic medium, as opposed to the optical media of CDs and DVDs. The hard disk is the most complicated mechanical device in the computer, so it is always enclosed in a firm metal case.

There are no user-serviceable parts inside the hard drive case. It consists of several metal disks, or platters, like a stack of pancakes. Each platter has a mechanical arm suspended above it, like the arm and stylus of an old vinyl record player. The end of the arm holds the read-and-write head, which does its magic from a microscopic distance off of the platter.

When referring to computer disk equipment, the drive is the hardware that spins, reads, and writes to the disk. Since the disks inside a hard drive are non-removable, the terms hard drive and hard disk are used interchangeably.

Advances in hard disk technology follow two paths: increasing the density of data on the platters and increasing the speed at which the data is written and read. The first hard disks in desktop computers held about 10 megabytes of data. Today’s hard disks, of the same physical size (and lower price), hold 500 gigabytes of data. In other words, the storage capacity of today’s disks are about 50 thousand times greater than they were 30 years ago.

A hard disk failure is described as a crash, because it usually means that the head has crashed into the platter. However, the word crash can be used to describe any situation where a computer stops working. It can refer to a program that locks up, or to a traffic overload which prevents a website from functioning.

hard disk driveComputers are usually assembled with one hard disk, which is sufficient for most users. But desktop cases usually have space to install additional hard disks, which may be advantageous for people who store a lot of audio and video files. The operating system keeps track of hard drives, and other drives as well, by assigning drive letters to them. Historically, the main hard drive which contains the operating system has always been designated as the C drive. Most casual home users never have a reason to change the default settings of the drives. Besides installing additional hard disks, it’s also possible for more advanced users to create virtual drives on a single physical hard disk. That is to say, you can divide the capacity of the C drive into two of more smaller virtual drives, each with their own letter-designation and name.


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